I'm a green and yellow kinda guy trying to help an older fellow with an MD. I'm somewhat perplexed since we dont have an operators manual and only an IT manual as a shop manual. He has no intentions of doing anything about changing that...

The proplem... The tractor has sat for several years. The fuel had solids in the tank and filters. It was dry and gritty.

I drained and flushed the tank a few times. The new fuel seems to really cut the old brown scale off the sides of the tank.

I purchased new filters and cleaned the water separator bulb and screen.

It is no problem to get fuel into the bulb, but it will not flow into the front filter unless I pressurize the tank (still flows slowly). Why is this? I dont have a diagram of any sort and am unclear as to what orfies the filter housing allows to flow where and why. How does the fuel get from the bulb into the front of the filter housing casting?

The second (toward rear of tractor) filter fills up and bleeds out fine.

I blew out the top of the water separator bulb housing with compressed air to get all the crud out. Fuel seems to flow in and out of it OK out of the two large ports. I can get nothing to go through the small pipe that sticks down into the mid section of the bulb. What is it for? Should air pass through?

Any general thoughts and advise for a guy that is accustomed to working on two cylinders? Can I get an overview of operation? I've read some of the old posts and learned some, but I'm still fairly confused...

I told my old friend to paint it green and yellow before I came back. Perhaps I'll have better luck that way? LOL JK

I will try to help you but most of my experience is with a Super MD and there was some variance in the fuel systems on these so if what I say doesn't make any sense that's probably why.

First off, will the tractor run on gasoline? If so it'll make what you're trying to do a lot easier. The frontmost filter is the final filter and the rearmost is the primary filter.

The small tube that goes into the glass bowl is for draining water out of the bottom of the bowl without removing it every time. There should be a small screw with little 'wings' on it on top of the bowl, releasing that screw will drain water from the bottom of the bowl via that tube.

Fuel flows from the tank to the bowl, from the bowl to the primary (rear) filter which is bled with the tractor not running and more that half a tank of fuel. It then flows to the rear of the injection pump where there is a small gear pump (which is why you're having to pressurise the tank to get fuel to flow past this point) and a filter screen. The filter screen looks something like a 2" length of 7/8" hex bar, the end of which screws off and brings the screen out with it. It points out from the side of the tractor. It then flows from the pump to the secondary or final filter (which is normally bled with the tractor running on gasoline). It then follows the almost conventional path to the injector pump and out to the injectors.

Hope that helped, Sam

Be sure to change the injection pump oil these tractors dont oil from the engine fuel dilutes yhe lube in the pump and then it cant develope enough fuel pressure blow white smoke miss and carry on hope this helps